U.S. Pat. No. 5,859,475 to Freyman et al. describes several ball grid array style packages for an integrated circuit device. The packages include a thin planar polyimide sheet. In one embodiment, a die pad and metal traces are formed on the upper surface of the polyimide sheet. An integrated circuit device is mounted on the die pad and is connected by bond wires to the metal traces. Metallized vias extend through the polyimide sheet and connect the metal traces on the upper surface of the sheet to metal traces on the opposite lower surface of the sheet. Solder balls are connected to the metal traces on the lower surface of the polyimide sheet. In another embodiment, a die pad and metal traces are formed on the upper surface of the polyimide sheet. The metal traces terminate in a metal land. Solder balls are directly attached to the backside of the metal land through apertures in the polyimide sheet. In both of these embodiments, bond wires, solder balls, metal traces, and metal-filled vias are used. Each of these features contribute to the cost of a package, and thus elimination of any of them will reduce costs. In addition, the packages do not include a means for enhanced thermal performance.